*2.4. Natural Conditions—Layer of the Landscape: Zoological Survey of the Interior Environment of the SA-CEFs*

The aim of the zoological survey was to carry out an inventory of invertebrate fauna in A-CEFs. As this is the first approach of this character to the SA-CEFs, the zoological survey was simplified to the extent that a) only indoor areas were studied, and b) only during the winter period (February/March 2014). This ensured that the number of potential taxa found was minimized as much as possible. Findings were expected of invertebrate species that are able to survive in similar types of environments for long periods of time (e.g., cellars, adits), but which usually live in suitable habitats outside this type of environment (socalled troglophilic or stygophilic species), as well as invertebrates that seek out similar environments for hibernation (hibernation). Probably the most representative-rich group were the expected so-called accidental guests of indoor spaces. Finds of invertebrates very closely adapted to living in underground spaces (troglobionts and stygobionts) were rather not expected.

Collecting was carried out in 39 SA-CEFs. Invertebrates of indoor spaces of the military fortification complex were studied by using conventional flashlights. Recorded species were examined on the walls and ceilings (spiders, butterflies, and moths) or on the floor under various objects like stones, remains of wood (snails, isopods). Collecting techniques as grids or kick sampling methods here were not used. In several cases, it was necessary to collect specimens for further determination by using entomological tweezers or an exhauster. Specimens were fixed in 70% alcohol or killed by vapors of ethyl acetate.

Subsequently, a partial objective of the faunistic survey was to select a suitable model group of invertebrate animals and characterize it with selected diagnostic features of zoocenoses (abundance, dominance, and frequency) [49]. Based on their abundance, we also performed inter-comparison of the SA-CEFs using multicriteria analysis. Selected independent environmental variables were included in the overall analysis. The environmental variables included altitude, humidity conditions inside the SA-CEFs, rate of human use, presence of organic material in the indoor environment, accessibility of the entrance, and the character of the SA-CEF's surrounding exterior environment. The collected data were processed using the R 4.0.5 program, calculating the similarity between the SA-CEFs using the Bray—Curtis index, the distribution of each sampling area depending on the selected environmental parameter using multivariate data analysis (MDS). SA-CEFs, where no live individuals were found, were not included in the analysis.

All data were recorded in a Microsoft Excel spreadsheet. Map outputs were processed in QGIS and zoological data and graphical outputs were processed in R 4.0.5.
